Military troops currently deployed in Operation Enduring Freedom face explicit dangers on the battlefield. But they may face a more insidious danger—in the form of post-traumatic stress disorder (PTSD)—in the years to come. Characterized by flashbacks or nightmares that replay the traumatic events, an avoidance of reminders of the ordeal or a hyperalert state, PTSD was first diagnosed as shell-shock after World War I. Now new research, published in the current issue of the journal Neuropsychology, suggests that higher IQ may help shield soldiers from PTSD.

Jennifer Vasterling of the Veterans Affairs Medical Center in New Orleans and colleagues studied 47 Vietnam veterans, 26 of whom suffer from PTSD. Though the extent of combat that the soldiers experienced proved the most important predictor of PTSD severity, the researchers found that veterans with higher pre-combat IQs were significantly less likely to have the disorder. Moreover, among veterans that developed PTSD, those with greater intellectual resources displayed less severe symptoms. The researchers note that actual premilitary measures of intellectual functioning are not readily available. They thus administered tests aimed at assessing the veterans' general information and word knowledge to estimate their IQs prior to serving in the military. Greater verbal skills, the authors suggest, could help soldiers better discuss their experiences in order to make sense of them and could help them establish more extensive networks for social support.

PTSD veterans also performed less proficiently on tasks requiring sustained attention, working memory and registration of new verbal information than did veterans without the disorder, according to the study. These findings resemble those reported for Gulf War veterans, suggesting that the cognitive problems suffered by veterans may be similar, even if their war experiences are not. Though the PTSD-related difficulties are mild compared to those posed by other neurological disorders such as Alzheimer's disease, Vasterling says, they "do trouble the veterans, who state that they interfere with daily life—especially their poor concentration."